Friday, November 20, 2009
"If Kudzu wasn't bad enough"...and other thoughts on exotic pests
Dr. Dan Suiter and Lisa Ames with the University of Georgia just sent out a pest alert on an insect called the "bean plataspid". I had never heard of a plataspid (pla TASS pid) before, so I looked in my well-worn copy of "How to Know the True Bugs" by James Alexander Slater--a very useful book for relatives of the box elder bugs--but with no luck. A quick check of the Internet revealed that Plataspids are Old World insects--hence not covered by my U.S. field guide.
Suiter and Ames recently received numerous samples of these insects swarming around homes in Georgia. Homeowners there are being repelled by not only the numbers, but also by a foul smell associated with the bugs. Turns out that this was the first known collection of these insects, known scientifically as Megacopta cribraria in the U.S. It is native to India and China, where it feeds on kudzu.
At this point many Southerners can be heard shouting "Glory be! A bug that eats kudzu! An answer to our prayers!" If you are not from the South, or are unfamiliar with kudzu, it is an invasive plant nightmare. Originally introduced in 1876 at the Centennial Exposition in Philadelphia, Pennsylvania in a Japanese government display garden. Planted widely as an ornamental vine for its abundant vegetation and sweet-smelling flowers, it was promoted as a forage plant by the Soil Conservation Service in the 1920s and 30s for erosion control. Bad idea. Kudzu smother trees and other plants under a solid blanket of leaves, by girdling woody stems and tree trunks, and by breaking branches or uprooting entire trees and shrubs through the sheer force of its weight. It grows at a rate of up to a foot a day.
Unfortunately for us, the bean plataspid does not appear to be a good solution to kudzu. Besides being a household pest on the order of the box elder bug or the Asian mulicolored lady beetle, the bean plataspid is a pest of numerous legume crops, including soybeans. The University of Georgia, Georgia Department of Agriculture, and U.S. Department of Agriculture consider it a potential agricultural pest and are partnering to take some regulatory action.
This appears to be the latest assault against the native fauna in our country. It's bad enough to have a new structural pest stinking up our homes, but when a foreign insect crosses the border into the U.S. it's generally forever. The fire ant landed on the sandy bay shores of Mobile, Alabama about 80 years ago and forever altered the ecology of the southern pine forest to the Texas prairies. We still don't know the full impact of fire ants on native wildlife and plant life, not to mention the American economy.
Last week I attended a conference on invasive pests, put on by the Texas Invasive Plant and Pest Council, in San Antonio. If there was ever a more discouraging subject for a biologist, I don't know what it is. In one of the talks, a botanist talked about his efforts to catalog and classify all the invasive foreign plants in Texas. He proposed classifying certain plants as some pests as "super watch" plants. "Super watch" plants are those which might possibly be removed from the Texas landscape before they become impossible to control.
I think the concept is a useful one for insects. By classifying certain insects as "Potentially Eradicable" pests, or putting them on some sort of "Super Watch" list, we accept responsibility for going after these pests. It seems to me that under our current system we have little incentive to go after new pests before they can get established.
Take the Formosan termite. We continue to watch helplessly as this pest becomes established in new sites around the South and in Texas. The potential economic impact of the Formosan termite is staggering, as it is at least twice as destructive as our native subterranean termite on homes, and an eater of live trees as well.
Ironically this is one pest that, in my opinion, could be controlled in isolated infestations before it becomes firmly established. We have dozens of sites in Texas where the Formosan termite is established on one or a few home properties. A determined effort to eradicate colonies with termite baits has, in my opinion, a good chance of succeeding in nipping many of these mini-invasions in the bud.
So what does all this have to do with pest management professionals? Knowing where a pest is found and how fast it is spreading is important for decision makers to know whether and how an invasive pest might be eradicated. Suiter and Ames are requesting PMPs in Georgia to report any sightings of the bean plataspid there. Here in Texas we are requesting PMPs to report new sightings of the rasberry crazy ant and the Formosan termite. These reports are very important to us and often form the basis for research dollars to work on solutions for these pests.
I will be working with Drs. Roger Gold and Robert Puckett this year attempting to delineate precisely where Formosan termites are present in the state of Texas. The research is being funded by the Texas Department of Agriculture and USDA's Animal and Plant Health Inspection Service. More information about the project will be forthcoming, but if you know of any suspected Formosan termite infestations we definitely want to know.
If only the Formosan termite could be coaxed into preferring kudzu.